The goal of this project is to further elucidate the relationships between structure and function for HCS and growth hormones. The functional requirements and effects of primary, secondary, tertiary and quaternary structure will be evaluated with regard to somatotropic, lactogenic, immunochemical and membrane binding activities. Physico-chemical assessment of structural parameters for the native, chemically and enzymatically modified forms of these protein hormones by absorption, fluorescence and circular dichroism spectroscopy, as well as by sedimentation, viscosity, thermal denaturation and electrophoretic and chromatographic means, will be employed. Similar studies will be performed on fragments of the hormones produced by chemical and/or enzymatic cleavage. Attempts will be made to generate hybrid molecular complexes with new structure-function relationships by non-covalent interaction (complementation) of natural fragments, as well as synthetic pieces. The principal proteins to be studied will include: human pituitary growth hormone (hGH), human choriomammotropin (HCS or hPL) and bovine pituitary somatotropin (bGH) plus such somatotropic and lactogenic hormones from mammalian and submammalian species as become available.